In a conventional exhaust gas recirculation system, as so many types of exhaust gas recirculation valves have been prepared to match the recirculation rate to various types of engine, the producing cost for each type of valve has inevitably increased. Each type of engine requires each rate of recirculation flow to match the amount of exhaust gas to the best performance of each engine and the requirement has been fulfilled by changing the dimension of the valve seat of the valve. Further in the conventional system, the cleaning of the valve seat with deposits, such as carbon has been troublesome, otherwise the valve might have miscontrolled the recirculation rate.